Is it a worthwhile response to the crisis in Libya?
The no-fly zone demonstrates international opposition to Gaddafi, but it is a comparatively weak military tool. Exclusion zones over Bosnia and southern Iraq in the 1990s were largely ineffective, but the no-fly zone in northern Iraq helped to protect the Kurds while they developed their autonomous administration. The success of the Libya operation will depend on the scale and intensity of the enforcement – and Gaddafi's forces presenting easily accessible targets. They may not oblige.
What does UN resolution 1973 allow them to do?
Members of the Security Council can "take all necessary measures" to protect civilians under threat of attack in Libya, but it expressly excludes "a foreign occupation force of any form".
Is it designed to protect civilians or support the revolution?
Ostensibly humanitarian though the intent of the no-fly zone is, the real motive, as made clear by President Obama and David Cameron, is regime change. The immediate test for the UN's intervention is how quickly – or even if – it can contain Gaddafi's forces, and how swiftly it can get in large amounts of medical aid. The latter depends on getting access to Benghazi and opening up a route from the Egyptian border.
Can the UN side also supply the rebels with arms?
When Cameron was asked about this, he said that the arms embargo in force covers the whole of Libya but pointed to the freedom to "take all necessary measures" as "very strong language, which allows states to take a number of military steps to protect people and harm those who are intending to damage civilians". However, privately the Cabinet is sceptical about the prospect of arming rebels.
Who is in charge?
Operation Odyssey Dawn is under the command of US Army General Carter Ham, commander of U.S. Africa Command. US Admiral Samuel Locklear is expected to take overall command. The admiral, who is based in Naples, is a commander with both the US Navy and Nato. The Allied Forces Southern Europe HQ in Naples is expected to be the operational hub for the no-fly zone, and Nato planners were tasked with producing a military strategy for the operation.
Which countries are participating?
France, Britain, the United States, Canada, Spain, Denmark, Norway, Qatar, Jordan and the UAE.
What forces do they have?
Both Britain and the US have submarines in the Mediterranean which launched Tomahawk missiles in the first strikes last night. Britain is also preparing Typhoon and Tornado aircraft, supported by the frigates HMS Westminster and HMS Cumberland, VC10 refuelling tankers and surveillance aircraft. The US has bombers and fighter planes, two amphibious assault ships and USS Providence. Spain is likely to provide F18 fighter bombers, France has Mirage and Rafale fighters and Norway is expected to send F16 fighters, all supported by submarines and surface vessels. Italy has offered the use of air bases.
What is the state of Gaddafi's forces?
Gaddafi's most significant weapons are his anti-aircraft missiles – notably the SA5A "Gammon" missiles, with a range of 150km. The bulk of up to 400 ground-to-air missiles remain under government control - which is why they were targetted last night. Gaddafi's aircraft are largely old and inoperable, but his navy is more formidable. Before this crisis, he had a 50,000-strong army, backed by 945 armoured personnel carriers and 800 tanks, many of which were considered unusable. He also has supporters who, reportedly, are prepared to be bussed into airfields and so used as human shields.
Why did it take so long to get into the air?
Until the UN vote was won, there could not be decisions on a military command structure, and therefore on deployments. Set-piece talks, such as those in Paris, make good TV. Video-conferencing would have been quicker, and could have been done on Friday. Thus, a day potentially wasted – and Gaddafi took full advantage.
Is Gaddafi now under a state of complete siege?
He has mounted a counter-offensive against the rebellion that threatened to overthrow him, but the international operation could restrict his freedom of movement even further. The no-fly zone should prevent him from crushing the rebellion in Benghazi. His country is also – under the lstringent sanctions agreed by the UN on Thursday – without much means to trade, earn or import food. His days, for this reason, are numbered, but the endgame could still be a long way off.
If Gaddafi's forces refuse to leave cities, how does the UN get them out?
With great difficulty. Strafing fighters on the open road is one thing; attacking them inside a city is quite another. Aerial attacks are liable to hit apartment blocks; even if they don't, Gaddafi's side could blow one up and claim it was a UN strike.
Could Gaddafi be allowed to remain in power if he submits to the force of the UN resolution?
Several leaders have said Gaddafi must go, but Resolution 1973 does not explicitly call for regime change or sanction a "foreign occupation force" – and no one is yet prepared to commit ground forces. Gaddafi's "ceasefire" has not headed off the threat of air-strikes but if he does comply, the international effort might not prove to be terminal – for the moment, at least. Saddam Hussein survived for more than a decade with two no-fly zones over Iraq from 1992, but he was never as isolated as Gaddafi is now.
When will Libya run out of food?
Libya is a net importer of food, and for the last month the UN World Food Programme has been warning that supply chains are close to collapse. The WFP launched a $39.2m (£24m) emergency operation to help feed more than one million people in Libya and those fleeing across borders into Tunisia and Egypt. The International Committee of the Red Cross (ICRC) called on all sides in Libya - including the multinational forces, Gaddafi's troops and the opposition - to abide by the principles of humanitarian law, particularly by distinguishing between civilians and fighters.
Is there a chance that the solution could be partition?
Libya is, like so many countries in the region, an artificial Western construct. If Gaddafi really dug his heels in, and his supporters proved as devoted as he claims, then partition could come – with a pariah, Gaddafi state in Tripoli, and a "Free Libya" in the east. But, with the oil in the east, and Gaddafi now surely an international untouchable beyond redemption, it is hard to see this being a long-term solution.
What about al-Qa'ida?
Strangely muted. John Jay Lebeau, a former CIA officer, now professor at the George C Marshall European Center for Security Studies in Germany, said: "The jihadists endorse the rebellion against the Gaddafi, but want the resistance to be purely Islamist in nature, resulting in eventual sharia rule. The idea of Western 'infidel' nations playing an important, perhaps even decisive, role in this conflict is utterly abhorrent to them. Al-Qa'ida in the Islamic Maghreb are frightened at the prospect of Western powers demonstrating this is not a jihadi-led or directed situation."
The contenders: Likely power-brokers in a post-Gaddafi Libya
Contenders are already emerging to lead Libya in a post-Gaddafi regime. New research provided to The Independent on Sunday by risk consultants Exclusive Analysis profiles potential key players in Libya's future.
Zaineb Al-Assam of Exclusive Analysis said: "Gaddafi will not step down voluntarily, and his opponents will accept nothing less than the removal of him and his allies. Tribalism and the weakness of the armed forces indicate that prolonged civil war is the most likely scenario for Libya."
Major General Abdul Fattah Younis al-Obaidi One of the army officers involved in the coup that saw Gaddafi seize power in 1969, the 67-year-old Interior Minister joined the rebels and ordered his troops to storm a security forces base in Benghazi last month. Major General Younis is a member of the powerful al-Obaidi tribe, and the interim government has described him as one of the "trustworthy" military persons who will lead the country for three months before elections are held.
Colonel Tarek Saad Hussein Not widely known until he defected and became one of seven former colonels to take charge of rebel forces in Benghazi. Colonel Hussein claims to be leading the operations against Gaddafi but maintains he is leading a popular uprising, not a military coup. In an interview last month, he said: "We hope to have a democratic state, not a military state. We are fed up with a military state. The military is only for protecting the nation — not for ruling."
General Abu Bakr Younis Jaber One of the original members of the Revolutionary Command Council and a long-time member of Gaddafi's inner circle. General Jaber's army experience makes him a likely candidate for leading a coup against Gaddafi. It is understood that he is under house arrest.
Abdul Salam Jalloud Another of the army officers in the 1969 coup and a friend of Gaddafi since school, he served as Libya's second in command until he was demoted in 1993 and ousted from the regime's elite inner circle two years later. Mr Jalloud has now publicly renounced Gaddafi.
Sheikh Akram el-Warfelli A senior member of the large Warfella tribe, which attempted a coup against Gaddafi in 1993. Once an ally of Gaddafi, he has now cut his ties with the Libyan leader. He said last month: "We tell the brother Gaddafi, well, he is no longer a brother. We tell him to leave the country."
Prince Mohammed El-Senussi The most likely candidate for heading a constitutional monarchy, which could emerge as a symbolic unifying force in post-Gaddafi Libya. He was seven when his great-uncle, King Idris, was overthrown by Gaddafi in 1969. The 48-year-old has lived in exile in Britain since 1988, and appeared on Arab media last month calling on Gaddafi to leave Libya and stop "massacring" his people.
Mustapha Abdul Jalil The former justice minister is now head of the Libyan interim government in Benghazi and likely to play a key role in the country's future.
Jamal Al-Hajji A human rights activist, writer, lawyer and long-standing opponent of Gaddafi who heads the 17 February Movement, named after the date of a heavy crackdown on opposition protests in Benghazi in 2006. Mr Al-Hajji holds dual Libyan and Danish nationality and has been imprisoned on various occasions; he is currently in jail on the pretext of a traffic offence.
Suleiman Abdul Qader The exiled chairman of the Muslim Brotherhood in Libya, he fled to London after a crackdown by Gaddafi in 1998. Mr Qader has called for "a reform inspired by civil society under the umbrella of a law which respects human rights".
Abdelhakim Belhaj Led the Libyan Islamic Fighting Group in the 1990s in several terrorist plots in Libya. Likely to lead a more radical alternative to the Muslim Brotherhood.
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